Hello, Thanks for posting your query. Most of the antiviral drugs, Antifungal like Griseofulvin, Anti tuberculosis like rifampin and other antibiotics like tetracycline,aztreonam,azithromycin,doxycycline,amoxicillin/clavulanate,cefazolin etc can interact with Loestrin 24Fe and reduce its effects. Use alternative contraceptives while taking these antibiotics. Hope it helps. Take Care!